Technical 500x intermittent problem

[Nanwood]

Hey everyone
sorry for the long post

hoping someone can point me in the right direction with a problem my mums 500x 1.4 turbo multiair automatic is having.
so Issues
check engine, and drive mode unavailable appear on dash, car loses power, starts misfiring and juddering until it comes to a standstill. Turn ignition off and back on again and it drives fine again. Engine management light stay of for a while but they goes away. Until the car does it again. It’s pretty frequent now. The cars probably done 50 miles since it started doing it.
faults in the computer are
p0301-00 cylinder 1 misfire
p0304-00 cylinder 4 misfire
p0300-00 random misfire
p130a-00 misfire 200

its also previosly had b106d-86 drive mode system signal invalid and various other ones like this.

long story short, Fiat main dealer advised, new battery, new outside temperature sensor, new plugs, new coils, oil and filter change and the multiair filter replaced. All of which has been carried out but has made no difference whatsoever.

ive read lots about the multiair unit issues and was wondering if this is what it sounds like to any of you guys? do they fail and then work fine again and then fail again. I’m reluctant to keep just throwing bits at it. Fiat were talking about poss injectors. Poss cam timing etc.

any advise much appreciated

cheers Olly

 

[Nanwood]

Anyone got any advice?

 

[s130]

Difficult to advise and I can (I think) post what the official 500X diagnostics are for these error codes. What concerns me is that the Fait Dealership should have more relevant and up to date info than I have. Meanwhile they appear to be suggesting "replace all" and that worries me.

Sometimes, even often, these multiple error codes are due to poor power. Bad battery, bad earthing (note many components can use local earths)

I'll be happy to post what I can from the official (dated) Fiat KeyLearn 500X 1.4 info but your Fiat dealer should have gone through all of these and if still stumped contacted Fiat UK Technical.

 

[dubmas]

Hi olly, any joy with the car, I have same faults. Thanks. Sam

 

[Kaz78]

I’m having same issues too, any more info would be appreciated

 

[s130]

I've not posted back further information since my last post as I've not seen the OP come back so assumed the dealer had fixed the problem.

Anyway below are what the workshop manual say for these errors.

But before venturing down any of these charts one really does have to check the battery, the clip on main earth post, main engine and chassis earth straps, etc. Check the plug coil pack connectors and lube/clear with switch/contact cleaner. Follow the wires from the cylinder head to any connectors further along and check those.

As we know these modern cars will throw all sorts of wobblies with any low power (volt or current) conditions so good connection and battery are a must.

334 - 500X 1.4 Turbo MultiAir Misfire random (performance or incorrect operation or component or system over temperature, misfire
1000 or misfire 200) P0300-00

34 - 500X 1.4 Turbo MultiAir Misfire cylinder 1 (performance or incorrect operation component or system over temperature, misfire
1000) P0301-00 & P0302-00 & P0303-00 & P0304-00

334 - 500X 1.4 Turbo MultiAir Misfire 200 (Component or system over temperature) P130A-00